CRYPTOGAMS 



369 



spores produced in multilocular sporangia can germinate without conjugating, 



as was seen to occur in Ulothrix among the Chlorophyceae. 



Ectocarpus siliculosus (Fig. 305) 'will serve as an example of the mode of con- 

 jugation of gametes produced from multi- 

 locular gametangia. The gametes are 

 IW9 II ijgifev-- -i similar in form, but their different be- 



J i y/ Nlllflsl'^ haviour allows of their distinction into 



male and female which are formed in dis- 



* " \ VF: : W < I tinct gametangia, borne on the same or 



I Y* : u ^ ' different plants. The female gamete be- 



comes attached to a substratum, and 

 numerous male gametes gather around 

 it (Fig. 305, 1). Ultimately a male 

 gamete fuses with the female to form a 

 zygote (Fig. 305, 2-9). This contains 

 after the fusion a single nucleus, but two 



Fio. 305. Ectocarpttii sH-iculonu*. 1, Female 

 .uaniete surrounded by a number of male 

 gametes ; seen from the side. 3-~>, Stages in 



the fusion of gametes. 6, Zygote after 24 

 hours. 7-9, Fusion of the nuclei in conjuga- 

 tion, as seen in fixed and .stained material. 

 (/-.'). after BERTHOLD ; 6-9, after OLTMANNS.) 



Flo. 304. A, Ectucarpustsiliculosus. Pluri- 

 locular sporangium liberating its con- 

 tents (after THURET). S, C, D, Sphace- 

 laria cirrhosa, development of the pluri- 

 locular sporangium (after REISKE). 

 (From OLTMANNS' Alyue.) 



chromatophores, and soon becomes attached and surrounded by a cell-wall ; it 

 grows into a new plant. 



In other Phaeophyceae the distinction between the two kinds of gametes is 

 expressed in their shape and size. The Cutleriaceae afford a particularly good 

 transition from isogamy to oogamy (*'-). 



2 B 



